Manufacture of asphalts



Patented June 14, 193

g MANUFACTURE or ASPHALTS Vladimir 1.. ships, New York, Arthur H. m'

Sunnyside, and J ames W.

Ramsay, New York:

N. Y., assignors to Socony-Vacuum Oil Oompany, Incorporated, New York, N. Y., a corporation 01'. New York Application March 6, 1937, Serial No. 129,376

14 Claims. gcl. 196-13) No Drawing.

This invention relates to asphaltic products of I the kind suitable for paving and similar purposes and relates especially to methods of producing such products. The ticularly to the production note from petroleum. L

It is customary to define the characteristics and properties of asphaltic materials by means of measurementsand. ratios, such as penetrationand ductility values, melting points, and temofrsuch asphaltic p'rodperature susceptibilities, the latter beingrepresented by. the ratio of penetrations at various temperatures, for instance, at 100 F. and 77F. or at 77 F. and 32 F. These measurements are made by standard methods of test ofthe American Society for Testing Materials. For example, penetration values are obtained by measuring the distanceoi penetration of various asphaltic materials by a specified needle loaded with a specified weight at a specified temperature for a specified time (see A. S. T. M. method No. D525,- Penetration of Bituminous Materials). Ductility values are obtained by measuring the elongation beiorebreaking of a specified sample pulled apart at a specified speed and at a specified temperature (see A. S. T. M. tentative method No. 4, 10118-321, Ductility of Bituminous Materials). Melting. points (softening points) are commonly determined by the ball and'ring method, which consists in filling a ring with asphalt and placing a steel ball oi specified weight in the center oi the asphalt, and then gradually heating the asphalt by means of hot water. The melting point is recorded-as the temperature at which the asphalt, under the load of the ball, touches the bottom of the water bath (see A. S. T. M. method No. D36-26, Softening Point for Bituminous materials). determinations given herein;

The properties represented by the above measurements are important from the standpoint of the present invention. It is important that asphaitic products employed ,for the purposes contemplated herein be oi proper hardness, as determined by penetrationtests, and that they be 02 low temperature susceptibility and of high due-- tility. Penetration is a measure of consistency). and Y hardness, serving primarily-to-clas siiy asf phalts into commercial grades of \various degrees of hardness. Temperature susceptibility (penetration ratio) indicates. the susceptibility of a product to change of hardness with change in temperature, that'is, its rate oi softening. It is desirable that, temperature susceptibility as exduced in part: a

The above methods are used for the;

pressed bythe above indicated ratio be asllow as possible, 1 since, ii it is too high, those asphalts' which have suitable hardness for-cold weather invention relates par-.

will flow and bedeformed in warm-weather and, conversely, those suitable for warm weather will be too brittle for cold weather use. Ductility' is a measure of the cementing power or, asphaltic ma-.

, terial, that is, itspower to hold together the aggregate or other mineral filler'in the final pavement compound, and is a very desirable property, contriiyiting extensively to the ability of pavements and similar asphaltic structures to withstand wear, disintegration, trafficshock, mechanr ical stresses due to temperature, weathering. and

the like. For example, asphalts having low-ductility, when used in paving mixtures, produce mixtures which separate and disintegrate under conditions of use, while asphalts of high ductility are capable of absorbing more filler than ordinary asphalts without objectionably impairing the mechanical strength of the mixture. I

The importance of the above properties inasphaltic material may be illustrated by the specifications and requirements of the State of Texas and the city of New York which are here repro- STATE OF TEXAS crrr on NEW YORK v 'Asrmumc Gauss-r (Tnumrrvn 24A-.7A) Penetration At 32 E, 100 grams, 5 sec.--Not less than 3.

M77 F., 100 grams, 5 sea-3040, @-50, 50-60 or 60-70 as called for.

At 100 F., 100 grams, sec.-Not. more than 4 .ti mes" that at 7711.

Ductility At 77 F., not less than 40 centimeters at penetration.

J 01m Emu Penetration At 32 n, 100 grams, 5 sea-Minimum 4. At 77 F., 100 grams, 5 sec. -100.

At 100 F., 100 grams, 3 sec-Maximum 3.25 times that at 77 F.

Ductility At 77 F., not less than centimeters.

Up to the present time, commercial manufacture of petroleum asphalt has been largely dependent upon the fortuitous presence of desirable properties in selected crude oils for the attainment of characteristics such as described and specified above; i. e., asphaltic or naphthenic crudes or asphaltic or naphthenic residues from mixed base crudes. Such crudes, roughly in the order of their desirability, are Mexican, Venezuelan, Smackover, Californian, and Coastal. The best stocks; e. g., Mexican, can be steam refined to produce asphalts, but for those grades of asphalt requiring low temperature susceptibility, as typified by the above specifications, the stocks must be air blown. Blowing results in loss of ductility. This tendency sometimes may be minimized to a limited extent by careful operation, but with a great many residual oils capable of being converted into otherwise desirable asphalts by blowing, no amount of care will serve to produce productsof desirable ductility. In order to obtain satisfactory ductility in asphalts requiring low temperature susceptibility, resort must be made to a very careful selection of crudes, even amongthe best Mexican and Venezuelan stocks, it being almost impossible to produce desired grades from domestic crudes.

It is an important object of the present invention to produce from commonly available petroleum stocks asphalt products which combine the above described desired properties, such as high ductility and low temperature susceptibility, and which are especially suitable for use in road surfaces and the like. It is an object to produce petroleum asphaltic products to meet specifications as desired without dependence upon the use of particular natural asphaltic stocks of specially selected quality. These objects are accomplished, and a novel product is produced, by a simple low cost novel process.

The present invention is based upon the discovery that asphaltidproducts having desirable properties, as above described, can be produced by blowing certain solvent tars to efiect conversion of the more naphthenic portions of the oil content of the tar into asphaltic material, and then adding to the blown tar an oil whose V. I. (viscosity indexsee article by Dean and Davis, Chemical and Metallurgical Engineering, October 1929, pages 618 and 619) is substantially higher than that of the oil which has been removed from the oil content of the tar by the aforesaid conversion.

It has been proposed to make asphaltic products by blowing solvent tars, but asphalts so produced are dependent for their properties upon the character of the tar employed,-the same as asphalts have been dependent upon the character of the crude oil used-and solvent tar asphalts bitumens from petroleum m1 asphaltic products l l 11 propane, and then add bee itated bitumens oils of desired pr: .s t0 produce asphalt products. process is complicated, slow and costly. The separated bitumens also are not in fact oil-free, and any oil that they contain is the more naphthenic portion of the oil content of the original material to which the propane precipitant was added, the more paraffinic portions havinggone oil with the propane.

The present invention, on the other hand, produces asphalts of good properties, controlled as desired, including high ductility, good (low) temperature susceptibility, and good penetration, and accomplishes this without necessity of removing any portion of the material by costly steps of solvent precipitation, vacuum distillation, or the like. In the present invention a portion of the oil content of the solvent tar is removed by conversion into asphaltic material, which is less expensive than removal by solvents or precipitants, increases yield of asphalt, reduces oil content, and effects such reduction in oil content by getting rid of the highly naphthenic portion of the oil content which would be the most objectionable in the asphalt and is not wanted. That is, in the present invention, and contrary to what occurs when propane precipitation is employed, the more naphthenic portions of the oil content of the tar are removed first by conversion into asphaltic material, the unconverted portions being less naphthenic and therefore more desirable in the asphalt. This increases yield and improves temperature susceptibility by improving the V. I. of the remaining oil content of the asphalt. Temperature susceptibility is then further improved by adding additional oil of appropriately high V. I. This invention also makes it possible to take advantage of the high ductility characteristic of solvent tar asphalts, and at the same time and at low cost to combine this property with good temperature susceptibility in a finished asphalt.

The preferred classes of solvent tars suitable for the uses of this invention are naphthenic tars resulting from the single or double solvent extraction of long or short residuums from asphaltic or mixed base crudes, employing naphthenic solvents of the class typified by cresylic acid, phenol, furfural, nitrobenzene, sulfur dioxide, and the like, or the substantial equivalent of such tars. However, although it is preferable to utilize solvent tars of relatively high asphaltic content and less asphaltic tars are relatively less useful, less asphaltic tars can be used to some extent and also can be reduced by distillation to obtain useful residues of fairly high asphaltic content, and can then be exposed to the steps of the process described herein. It is the class of solvent tars defined herein that is covered by the term as used in the claims. These tars are not the same or equivalent to propane precipitated bitumens. These solvent tars normally and preferably contain some asphaltic matter before blowing; i. e., asphaltenes and resins. They also contain oil. The greater proportion of the oil content of the tars is highly naphthenic and readily forms asphaltic matter upon blowing. The most naphthenic portions; i. e., the oil that would. be the most undesirable in the finished asphalt, is the most unstable and therefore is the first to be removed by conversion upon blowing. The oils contained in solvent tars have very low he the presence of these highly naphthenic or low cent iii-dices, as they include a large proporviscosity index oils which to a great extent im parts a high temperature susceptibility to asphalts derived from solvent tars. In the present invention the oils "present in solvent tars are 6 selectively converted and/or removed by blowing the tars with air or other oxidizing gas to a controlled extent, followed by addition of. oil of better V. I.- By proceeding in thismanner the most undesirable naphthenic constituents are removed i while the more paramnic oils remain, thereby producing an index.

The oil content of the solvent tars is usually so highly naphthenic that the blowing operation is oil content of improved viscosity in itself not capable of producing an asphalt of suiiioiently low temperature susceptibility. It is and degree of paraiiinicity of these added oils can be varied with the result that the process can be easily controlled both as to extent of blowing and the amount and character of oil addition.

Ordinarily the added oil will have not only. a higher viscosity index than that of the oil originally present in the tar, but will havea viscosity index higher than that of the improved oil re- 01 maining in .the' tar after the blowingtreatment.

Because of the extremely low V. I. of the oil content of the solvent tars, good temperature sus- "ceptibility improvement can ordinarily be obtained with diluent oils ranging down to zero V. I. The viscosity of the oil added to the solvent, tar does not materially afiect the quality of the final asphalt, but light oil, just. passing flash point requirements and the like, is ordinarily used, because such oil is cheaper than more viscous'oil and less of it is required to bring the asphalt to proper penetration. v The solvent tar may be blown to any suitable extent, as desired, but,is preferably blown to a point beyond the penetration and/or melting 5 point specifications desired in the finished asphalt, and is then brought back to the desired or specified values by adding oil of proper viscosity index characteristics, which causes a definite improvement or lowering of the temperature susceptibility for". the specified penetration value or melting point. The blowingis conducted at elevated" temperatures, say 400 500 F. in the known manner of asphalt blowing. Asa specific example of this manner of proceeding, the solvent 5. tar may be blown to a penetration value of 30 at 77 F., and may thnbe cutback with a suitably high viscosity index oil to lower the temperature susceptibility and raise the penetration value to commercially useful grades: the hardest commercial 'grade having a penetration value of about 40 at 77 F. The solvent tar may be blown to the point of apparent loss of ductility, i. e., to a point I where the ductility is so low that it records as zero on the ductility testing machine, and then the ductility and penetration values can be raised by the addition of the oil of suitably high viscosity index. In such a case, the upper limit of hard blowing is where the ductility is too low even after adding the oil to the blown tar, which ordinarily occurs when the tar is blown to a melting point of about 220 F. L.

As examples illustrative of the invention, the following data are given showing four diflerent 7g asphalt'products embodying the invention.

1 Composition 4 I Percent Percent Pei-cent Percent Solvent tar blown- 156 F., M. P.- r 87.5 to 170 F., M. P 80.0 81.5 "86.2 Blending oil No. l 13. 8 12. 5 Blending oil No. 2 '14. 0 l8. 5

e l K Properties Percent Ifercent Percent Percent ,M elting point a. a 3. y

F 125 11 124.5 115.5 Pen. 77 F., 100 g.,

sec 53 103 Pen. 32 ii, g., r

5 sec 4 8 0 7 Pen. 32 F., 200 g.,

60 Sec.-..' 20 32 23 36 Ductility 77 F., cms 100+ 100+ 100+ 100+ In the above examples blending oil No. l is a dis- I ,tillate derived from mixed base crude having an A. P. I. gravity of 25.9, flash C. O. C 365 F., 8. U." viscosity 113.6 at 100 F., and viscosity index 75. Blending oil 'No. 2 is a. gas oil distillate from an asphaltic base crude of A. P. I. gravity 21.3", flash c. o. o. 335 Ff, s. U. and viscosity index 25.

We claim: L l. A process for manufacturing an asphaltic material which comprises air blowing a solvent tar to convert a portion of. its naphthenic oil content into asphaltic material, and adding to said blown tar an oil of viscosity index higher than the viscosity index of the original naphihe'nic' oil -content of the solvent tar.

2. A process for manufacturing an asphaltic material ofhigh ductility and low temperature susceptibility which comprises airblowing a solviscosity 144 at 190 F;

vent tar at elevated temperature to convert the the less naphthenic portions unconverted; and...

improving the temperature susceptibility by adding to said blown tar an oil less naphthenic than the remaining naphthenic oil content of the e blown solvent tar. 3. The method of making asphalt whichcomprises altering the morenaphthenic portion of the oil content of a solvent tar by oxidizing same into asphaltic material; and replacing said removed portion with an oil less naphthenio than the oil which was oxidized.

4. A process for obtaining an asphaltic material having a low susceptibility ratio and a high ductility value which comprises obtaining a=solvent tar containing an oil of a low viscosity index by solvent refining a petroleum product containing naphthenic constituents, oxidizing the more naphthenic .portion on said tar into asphaltic matter whileleaving the less naphthenic portion unconverted, and adding to said tar an oil having a viscosity index higher than the viscosity index of said first named oil.

' 5. A process for obtaining an asphaltic material having a low susceptibility ratio and a high duc- .tility value which comprises solvent. refining a petroleum residue to ,obtain a solvent tar containing,0ils of low viscosity index, air blowing said tar until a major portion of said oils is oxidized higher viscosity index than that of said remaining unconverted portion of oil.

6. A process for manufacturing an improved asphaltic material which comprises solvent refining a petroleum residue to obtain a solvent tar, air blowing said tar to an excessively low penetration value and an excessively high melting point, and adding an oil of. relatively high viscosity index to said air blown tar, thereby raising the penetration value and lowering the melting point of the tar-oil mixture to predetermined desirable values and simultaneously lowering the susceptibility ratio of said mixture below that normally existing in said tar at said values.

'7. A process for manufacturing an improved asphaltic material which comprises solvent refining a petroleum residue to obtain a solvent tar,

air blowing said tar to a penetration value of not more than 30 at 77 F., and adding an oil of relatively high viscosity index to said air blown tar, thereby raising said penetration value to a predetermined desirable value not less than at 77 F. and simultaneously lowering the susceptibility ratio of the tar-oil mixture below that nor-' mally existing in said tar at said predetermined value.

8. A process for manufacturing an improved asphaltic material which comprises solvent re-. fining a petroleum residue to obtain a solvent tar, air blowing said tar to apoint of apparent loss of ductility and to an excessively low penetration value, and adding an oil of relatively high viscosity index to said air blown tar, thereby raising said ductility and penetration values to predetermined desirable values and simultaneously lowering the susceptibility ratio of. the tar-oil mixture below that normally existing in said tar at said predetermined values.

9. A process for manufacturing an improved asphaltic material which comprises distilling solvent tars having a relatively low asphaltic content to produce a tar having a relatively high asphaltic content, said tar containing an oil of relatively low viscosity index, air blowing said tar, and adding an oil of relatively high viscosity index to said blown tar.

10. The method of making asphalt of high ductility and low penetration ratio which oomprises air blowing a solvent tar to an asphalt of substantially zero ductility, and adding to said hard blown tar an oil of viscosity index higher than that of the oil content of. the solvent tar before blowing. I a

11. An improved asphaltic material comprising an air blown solvent tar asphalt and an oil of.

viscosity index higher than that of the oil content of the solvent tar prior to air blowing.

12. An improved asphaltic material comprising an air blown solvent tar and an oil of relatively high viscosity index, said air blown tar being free of oil of the nature of the more naphthenic portion of the oil present in the tar prior to air blowing.

13. An improved asphaltic material having a relatively high ductility value and .a relatively low susceptibility ratio comprising an air blown solvent tar and an oil of. relatively high viscosity index not less than 0, said air blown tar containing a small portion of an oil of relatively low viscosity index which was present in the tar prior to blowing.

VLADIMIR L. SHIPP. ARTHUR H. BOENAU. JAMES W. RAMSAY. 

